A poet and a scientist were traveling together on a plane. The scientist was bored and said to the poet, "Hey, you, do you want to play a game? I'll ask you a question, and if you get it wrong, you give me $5. Then, you ask me a question, and if I can't answer it, I'll give you $5."
The poet thought about this for a moment, but he decided against it, seeing that the scientist was obviously a very bright man. He politely turned down the scientist's offer.
The scientist, who was really bored, tried again. "Look, I'll ask you a question, and if you can't answer it, you give me $5. Then you ask me a question, and if I can't answer it, I'll give you $50."
The poet agreed. "Okay," the scientist said, "what is the exact distance between the Earth and the Moon?"
The poet, obviously not knowing the answer, didn't stop to think about the scientist's question. He took a $5 bill out of his pocket and handed it to the scientist.
The scientist happily accepted the bill and promptly said, "Okay, now it's your turn."
The poet thought about this for a few minutes, then asked, "All right, what goes up a mountain on three legs, but comes down on four?"
The bright glow quickly vanished from the scientist's face. He thought about this for a long time, taking out his notepad and making numerous calculations. He finally gave up on his notepad and took out his laptop, using his Multimedia Encyclopedia. As the plane was landing the scientist gave up. He reluctantly handed the poet a $50 bill.
The poet accepted it graciously, getting ready to stand up. "Wait!" the scientist shouted, "you can't do this to me! What's the answer?"
The poet looked at the scientist and calmly put a $5 bill into his hand.